A device and method are provided for isolating and culturing microorganisms from a bulk fluid sample. The torque fluctuation damping elastic member 15 includes a pair of rubber members 15A and 15B which sandwich a support portion 24 of the pulley member 13 under equal elastic forces from the front and rear in the axial direction of the pulley member 13 to joint the hub with the pulley member 13 elastically. However, still today, strongly magnetic material detaching from the roller is a problem that has been tried to be resolved by introducing the magnets inside the cylinders, in only one area thereof, in such a way that when the material is rotated on the cylinder and moves away from the magnetised area, it falls as a result of gravity. Embodiments of the invention may be useful in precision stage devices, for example, lithography devices such as steppers and scanners. The polishing pad includes at least one substantially straight polishing pad edge along a perimeter thereof corresponding to the at least one substantially straight backing pad edge when the polishing pad is attached to the backing pad. When the human body comes into contact with an electrode, the modulated signal transmitted through the human body is amplified by a pre-amplifier, demodulated by a demodulator circuit, and shaped by a comparator.